The number 21307
21307 is a composite number with 8 divisors. Its prime factorisation is 11 × 13 × 149. Divisors (8): 1, 11, 13, 143, 149, 1639, 1937, 21307.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21307: a Harshad number: divisible by its digit sum 13.
- 2
21307 is composite. Its prime factorisation is
- 3
The divisors add up to 25200; without 21307 itself that is 3893, so 21307 is deficient (3893 is less than 21307). Euler's totient φ(21307) = 17760 numbers up to 21307 share no factor with it.
- 4
The digits of 21307 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 87 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21307 = 11 \times 13 \times 149 \]
21307 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 25200 |
| Euler totient φ(n) | 17760 |
| Square | 453988249 |
| Cube | 9673127621443 |
| Square root | 145.969175 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 87 |
| Scientific notation | 2.1307 × |
21307 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand three hundred and seven |
| Binary (base 2) | 101001100111011 |
| Octal (base 8) | 51473 |
| Hexadecimal (base 16) | 533B |
| Base 3 | 1002020011 |
| As time | 21307 seconds = 5 h 55 min 7 s |
Is 21307 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 6) | A number is divisible by 7 if double the last digit and subtract it from the rest: the result is a multiple of 7. |
| 8 | No (remainder 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 7) | A number is divisible by 10 if the last digit is 0. |
| 11 | Yes (21307 ÷ 11 = 1937) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21307 a prime number?
No. 21307 = 11 × 13 × 149, so it is divisible by 11.
What are the factors of 21307?
1, 11, 13, 143, 149, 1639, 1937, 21307.
What is 21307 in binary?
101001100111011 (hexadecimal 533B, octal 51473).
What is the square root of 21307?
About 145.9692.
Is 21307 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 21307?
21307 is a Harshad number: divisible by its digit sum 13.